EP0580206A1 - Détecteur d'oxygène dans un domaine étendu - Google Patents

Détecteur d'oxygène dans un domaine étendu Download PDF

Info

Publication number
EP0580206A1
EP0580206A1 EP93201944A EP93201944A EP0580206A1 EP 0580206 A1 EP0580206 A1 EP 0580206A1 EP 93201944 A EP93201944 A EP 93201944A EP 93201944 A EP93201944 A EP 93201944A EP 0580206 A1 EP0580206 A1 EP 0580206A1
Authority
EP
European Patent Office
Prior art keywords
oxygen
electrodes
layer
pair
porous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP93201944A
Other languages
German (de)
English (en)
Other versions
EP0580206B1 (fr
Inventor
Seajin Oh
Jose Joseph
Earl Wayne Lankheet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Motors Liquidation Co
Original Assignee
General Motors Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Motors Corp filed Critical General Motors Corp
Publication of EP0580206A1 publication Critical patent/EP0580206A1/fr
Application granted granted Critical
Publication of EP0580206B1 publication Critical patent/EP0580206B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/417—Systems using cells, i.e. more than one cell and probes with solid electrolytes
    • G01N27/419—Measuring voltages or currents with a combination of oxygen pumping cells and oxygen concentration cells

Definitions

  • the present invention generally relates to automotive exhaust gas oxygen sensors of the solid electrolyte, electrochemical type. More particularly, this invention relates to thin film internal reference solid electrolyte oxygen sensors which are capable of rapid linear response to both lean and rich fuel conditions, and which are further characterised by being formed in a planar configuration as specified in the preamble of claim 1, for example as disclosed in US-A-4,863,584 Gas sensors are used in a variety of applications which require qualitative and quantitative analysis of gases.
  • the oxygen concentration in the exhaust gas of an engine has a direct relationship to the air-to-fuel ratio of the fuel mixture which is supplied to the engine.
  • oxygen gas sensors are used in automotive internal combustion control systems to provide accurate oxygen concentration measurements of automobile exhaust gases for determination of optimum combustion conditions, maximization of fuel economy, and management of exhaust emissions.
  • oxygen sensors should have a rapid response time at temperatures ranging between about -40°C and 800°C.
  • the electrochemical type of oxygen sensor typically used in automotive applications utilises a thimble-shaped electrochemical galvanic cell operating in the potentiometric mode to determine, or sense, the relative amounts of oxygen present in the exhaust from an automobile engine.
  • This type of oxygen sensor includes an ionically-conductive solid electrolyte material, typically yttria-stabilised zirconia, a porous electrode coating on the exterior of the sensor which is exposed to the exhaust gases, and a porous electrode coating on the interior of the sensor which is exposed to a known concentration of reference gas.
  • the individual components are typically fabricated by conventional processes such as moulding, grinding and high-temperature firing.
  • potentiometric oxygen sensors are employed in the exhaust gas system of an internal combustion engine to determine qualitatively whether the engine is operating at either of two conditions: (1) a fuel-rich or (2) a fuel-lean condition, as compared to stoichiometry. After equilibration, the exhaust gases created by engines operating at these two operating conditions have two widely different oxygen partial pressures. This information is provided to an air-to-fuel ratio control system which attempts to provide an average stoichiometric air-to-fuel ratio between these two extreme conditions. At the air-to-fuel stoichiometric point, the oxygen concentration changes by several orders of magnitude. Accordingly, potentiometric oxygen sensors are able to qualitatively indicate whether the engine is operating in the fuel-rich or fuel-lean condition, without providing more specific information as to what is the actually air-to-fuel ratio.
  • diffusion limited current oxygen sensors have a pumping cell and an oxygen storage cell for generating an internal oxygen reference source.
  • a constant electromotive force is maintained between the storage cell and the pumping cell so that the magnitude and polarity of the pumping current can be detected as being indicative of the exhaust gas composition.
  • An oxygen sensor according to the present invention is characterised by the features specified in the characterising portion of claim 1 It is an object of this invention to provide an oxygen sensor for an internal combustion engine which is capable of accurately determining the air-to-fuel ratio over a wide range of operating conditions including both fuel-rich and fuel-lean, whilst also being constructed to be more readily manufactured under mass-production processing conditions.
  • such a wide-range oxygen sensor should operate at least partially in the diffusion limited current mode so as to provide an output which is proportional to the oxygen partial pressure in exhaust gas from an engine.
  • an oxygen sensor for an internal combustion engine which is capable of accurately determining the air-to-fuel ratio under both fuel-rich and fuel-lean operating conditions - what is termed a wide-range oxygen sensor.
  • the oxygen sensor has a planar construction produced by plasma-spray deposition methods which facilitates manufacture of the oxygen sensor under mass-production processing conditions.
  • the oxygen sensor includes a suitable substrate, an electrochemical storage cell and an electrochemical pumping cell disposed on the substrate in spaced-apart relation to each other, and an electrochemical reference cell formed between the storage and pumping cells.
  • the electrochemical storage cell and the electrochemical pumping cell share a solid electrolyte layer which facilitates processing and reduces manufacturing costs. "Ionic cross-talk" between the electrochemical storage cell and the electrochemical pumping cell is held to an insignificant level by the particular geometry of the solid electrolyte layer.
  • the electrochemical storage cell has a pair of electrodes disposed on opposite sides of the solid electrolyte layer.
  • An oxygen storage layer is disposed on the substrate and contacts a lower of the two electrodes.
  • the upper electrode contacts the exhaust gas to be measured.
  • the electrochemical storage cell is driven by a constant current source so as to pump oxygen into the oxygen storage layer thereby maintaining a predetermined oxygen partial pressure therein.
  • the predetermined oxygen partial pressure serves as a reference partial pressure for the oxygen sensor, and is preferably within at least one order of magnitude from one atmosphere.
  • the electrochemical pumping cell also has a pair of electrodes positioned on opposite sides of the solid electrolyte layer.
  • the electrochemical pumping cell has a diffusion layer disposed on the substrate which contacts a lower of the two electrodes of the electrochemical pumping cell. Again, the upper electrode contacts the exhaust gas to be measured.
  • oxygen and reducing gases in the exhaust gas are able to diffuse laterally into the diffusion layer.
  • the electrochemical pumping cell is driven by a variable voltage source connected to its electrodes so as to pump oxygen into and out of the diffusion layer. As described more fully below, it is the current flow resulting from this variable voltage source which is measured and which is indicative of the exhaust gas content. Oxygen is pumped into or out of the diffusion layer, depending upon the oxygen partial pressure within the diffusion layer which is predisposed to correspond to the oxygen partial pressure of the exhaust gas.
  • the electrochemical reference cell is formed between the lower electrodes of the electrochemical storage and pumping cells, and serves to monitor the oxygen partial pressure in the diffusion layer of the electrochemical pumping cell relative to the predetermined oxygen partial pressure in the oxygen storage layer of the electrochemical storage cell.
  • the electrochemical reference cell produces a voltage output based upon the potential difference between the lower electrodes which is created by the difference in oxygen partial pressure between the diffusion cell and the oxygen storage cell. This potential difference is sought to be maintained at a level corresponding to the air/fuel stoichiometric point.
  • This voltage output can then be used as a feedback to the variable voltage source of the electrochemical pumping cell so that the electrochemical pumping cell is directed to maintain an oxygen partial pressure in the diffusion layer at a level approximately equal to the air/fuel stoichiometric point.
  • an ionic current flows through the electrochemical pumping cell which is proportional to the oxygen concentration in the exhaust gas.
  • the direction of the current flow is dependent upon whether the air/fuel mixture is fuel-rich or fuel-lean.
  • the electrochemical pumping cell is forced to pump oxygen into the diffusion layer, whilst a fuel-lean air/fuel mixture (i.e., oxygen-rich) results in the electrochemical pumping cell being forced to pump oxygen out of the diffusion layer.
  • fuel-rich i.e., oxygen-poor
  • the solid electrolyte layer is preferably an yttria-stabilised zirconia (YSZ) material which permits the transfer of oxygen ions therethrough under the influence of the electrical circuits.
  • the oxygen storage and diffusion layers are preferably porous layers which permit the diffusion of oxygen molecules therethrough.
  • the oxygen storage and diffusion layers are both screen printed on the substrate.
  • the electrodes are each preferably formed of porous platinum using known sputtering methods.
  • the substrate is preferably a dense substrate which prevents oxygen ions and molecules from diffusing out through the base of the oxygen sensor.
  • the construction of the oxygen sensor and processing method of this invention used to build the oxygen sensor both serve to reduce manufacturing costs, whilst also making the oxygen sensor more readily producible under mass-production conditions.
  • the processing steps include depositing a pair of spaced-apart porous layers, corresponding to the oxygen storage layer of the electrochemical storage cell and the diffusion layer of the electrochemical pumping cell, onto the dense substrate using known screen-printing methods and firing. If the dense substrate is formed from dense YSZ, an insulating layer of porous ceramic material is then deposited by plasma-spray deposition everywhere on the substrate except on the porous layers. A first pair of porous platinum electrodes are then sputtered onto the insulating layer so that each of the electrodes is in contact with a corresponding one of the porous layers.
  • Two narrow aluminium oxide layers are then formed by plasma-spray methods to determine the exposed area of the first electrode and also to prevent leakage of oxygen on the first electrodes.
  • the solid electrolyte layer is then formed by plasma-spray deposition methods to cover essentially all of the electrodes except for portions left bare for serving as electrical contacts to external electronic circuits.
  • the thickness of the electrolyte layer is limited relative to the distance between the porous YSZ layers so as to minimise the ionic cross-talk between the two porous YSZ layers.
  • a second pair of porous platinum electrodes is sputtered onto the solid electrolyte layer so that each one is in ionic communication with a corresponding one of the first pair of electrodes through the solid electrolyte layer.
  • the oxygen sensor provides a relatively low-cost, high-performance oxygen sensor whose output is proportional to the oxygen partial pressure in the exhaust gas.
  • the horizontal structure is a more practical construction for wide-range oxygen sensors in that the structure does not require intricate reference chambers or the vertical assembly of many layers.
  • the oxygen sensor is capable of sensing small changes in the oxygen partial pressure of the exhaust gas corresponding to operation of an engine in either the fuel-lean or fuel-rich condition. Finally, whether the engine is operating fuel-lean or fuel-rich will be shown by the direction of current flow through the electrochemical pumping cell.
  • a wide-range oxygen sensor which operates partially in a diffusion limited current mode to provide an output which is proportional to the oxygen partial pressure in a gas mixture which is sensed, such as the exhaust gas of an automotive internal combustion engine.
  • the wide-range oxygen sensor is capable of rapidly and accurately sensing the exhaust gas oxygen partial pressure whilst the engine is operating in either the fuel-rich or fuel-lean condition so as to determine the air-to-fuel ratio of the pre-combustion fuel mixture.
  • the wide-range oxygen sensor is constructed to have a planar structure that facilitates its manufacture using known thermal deposition techniques.
  • the wide-range oxygen sensor of the present invention is characterised as being of relatively low cost and readily producible under mass-production conditions.
  • the wide-range oxygen sensor is also rugged for operating in the severe environment of an exhaust system of an automobile.
  • a wide-range oxygen sensor 10 in accordance with a preferred embodiment of this invention.
  • the structure of the wide-range oxygen sensor 10 is planar and does not include a chamber or recess for use as a gas reference device, as noted with the prior-art diffusion limited current oxygen sensors.
  • the wide-range oxygen sensor 10 of the present invention instead relies upon the use of porous layers of ceramic material to store oxygen as references for determining oxygen partial pressure in the exhaust gas.
  • the wide-range oxygen sensor 10 includes a substrate 11 which is preferably formed from dense ceramic material, and more preferably dense yttria-stabilised zirconia (YSZ) which serves as a barrier to the diffusion of oxygen and other molecules through the wide-range oxygen sensor 10.
  • YSZ dense yttria-stabilised zirconia
  • electrochemical storage cell and an electrochemical pumping cell are formed on the substrate 11 in spaced-apart relation to each other.
  • the electrochemical storage cell is shown to be on the left-hand end of the wide-range oxygen sensor 10 whilst the electrochemical pumping cell is shown to be on the right-hand end of the wide-range oxygen sensor 10.
  • the electrochemical storage cell and the electrochemical pumping cell share a solid electrolyte layer 26 formed from a conventional solid electrolyte material, preferably a very dense YSZ.
  • the solid electrolyte layer 26 permits the transfer of oxygen ions therethrough under the influence of an electric current. This arrangement, and particularly the use of a single electrolyte layer, facilitates fabrication of the wide-range oxygen sensor 10, thereby reducing manufacturing costs whilst also enhancing the quality and reliability of the wide-range oxygen sensor 10.
  • an insulating layer of alumina 16 is preferably provided to discourage ionic flow between the solid electrolyte layer 26 and the substrate 11.
  • "Ionic cross-talk" between the electrochemical storage cell and the electrochemical pumping cell is held to an insignificant level by limiting the thickness of the solid electrolyte layer 26.
  • the relative thinness of the solid electrolyte layer 26 enhances ionic flow through the electrochemical storage and pumping cells and, in conjunction with a sufficient lateral distance between the electrochemical storage and pumping cells, also inhibits ionic transfer between the electrochemical storage and pumping cells.
  • a pair of insulating band layers 22 and 24 are selectively provided between the solid electrolyte layer 26 and the other elements of the wide range oxygen sensor 10, which are described in detail below, to prevent ionic or electrical leakage at the periphery of the solid electrolyte layer 26.
  • the electrochemical storage cell includes an upper and lower porous platinum electrode 28 and 20, respectively, disposed on opposite sides of the solid electrolyte layer 26.
  • the porosity of the electrodes 28 and 20 permits the diffusion of oxygen molecules therethrough.
  • An oxygen storage layer 14 is formed from a porous ceramic material whose coefficient of thermal expansion closely matches that of the other components of the electrochemical storage cell.
  • the oxygen storage layer 14 is disposed directly on the substrate 11 and contacts the lower electrode 20. "Porous" in this sense is a relative term indicating the ability of the oxygen storage layer 14 to contain oxygen molecules.
  • the porosity of the YSZ oxygen storage layer 14 permits the accumulation and flow of oxygen molecules within the oxygen storage layer 14.
  • the solid electrolyte layer 26 is positioned between the upper and lower porous platinum electrodes 28 and 20 as shown to form an ionic current path between the upper and lower porous platinum electrodes 28 and 20.
  • the electrochemical storage cell is driven by a constant-current source 32 to pump oxygen into the oxygen storage layer 14 from the exhaust gas which contacts the upper porous platinum electrode 28 at a rate which is sufficient to maintain a predetermined oxygen partial pressure in the oxygen storage layer 14.
  • the current from the constant current source 32 must be such that the rate at which oxygen is pumped into the oxygen storage layer 14 is sufficient to compensate for any leakage from the oxygen storage layer 14, which is generally of the order of about 1 to 100 milliamperes.
  • the oxygen partial pressure in the oxygen storage layer 14 is within at least one order of magnitude from one atmosphere to provide a stable oxygen partial pressure value.
  • the oxygen partial pressure within the oxygen storage layer 14 of the electrochemical storage cell serves as the reference partial pressure for the operation of the wide range oxygen sensor 10.
  • the electrochemical pumping cell also has upper and lower porous platinum electrodes 30 and 18, respectively, which are positioned on opposite sides of the solid electrolyte layer 26.
  • the electrochemical pumping cell has a diffusion layer 12 formed from a porous ceramic material, according to the same criteria as that of the oxygen storage layer 14, so as to permit the diffusion of oxygen molecules through the diffusion layer 12.
  • the diffusion layer is disposed directly on the substrate 11 and contacts the lower porous platinum electrode 18 of the two porous platinum electrodes 18 and 30 of the electrochemical pumping cell. As can be seen in Figure 12, the diffusion layer 12 is partially exposed to the exhaust gases to allow oxygen molecules to diffuse directly into the diffusion layer 12.
  • the electrochemical pumping cell is driven by a variable voltage source 34 which is connected to the porous platinum electrodes 18 and 30 of the electrochemical pumping cell to pump oxygen into and out of the diffusion layer 14 as necessary to maintain a predetermined oxygen partial pressure in the diffusion layer 14. Because the diffusion layer 14 is partially exposed to the exhaust gases, oxygen diffuses laterally into the diffusion layer 12 so that the diffusion layer 14 is predisposed to have an oxygen partial pressure equal to that of the exhaust gas. The porosity and edge geometry of the diffusion layer 12 determines the oxygen diffusion rate into the diffusion layer 12 from this exposed portion.
  • variable voltage source 34 functions to maintain the oxygen partial pressure in the diffusion layer 12 at a level corresponding approximately to the air/fuel stoichiometric point, instead of the actual partial pressure corresponding to the exhaust gas.
  • an electrochemical reference cell is formed by the lower porous platinum electrodes 20 and 18 of the electrochemical storage and pumping cells, respectively.
  • the solid electrolyte layer 26 also lies between the lower porous platinum electrodes 18 and 20 to complete the ionic circuit of the electrochemical reference cell.
  • the electrochemical reference cell is able to sense the difference in oxygen partial pressures in the oxygen storage layer 14 and the diffusion layer 12.
  • the electrochemical reference cell produces a voltage output based upon the potential difference between the lower porous platinum electrodes 18 and 20 created by the difference in oxygen partial pressure between the diffusion cell 12 and the oxygen storage cell 14.
  • This voltage output which is shown being detected by a voltmeter 38, can then be used as a feedback to the variable voltage source 34 of the electrochemical pumping cell so that the electrochemical pumping cell is directed to maintain an oxygen partial pressure in the diffusion layer 12 at a level corresponding approximately to the air/fuel stoichiometric point.
  • a voltage of approximately 0.45 volts corresponds to the potential difference created between oxygen partial pressure in the diffusion layer 12 at the stoichiometric point and the oxygen partial pressure at one atmosphere or more in the oxygen storage layer 14.
  • oxygen ions flow through the electrochemical pumping cell in a direction opposite to the current flow between the porous platinum electrodes 18 and 30.
  • This ionic flow which is shown being detected by an ammeter 36 in Figure 24, is proportional to the oxygen concentration in the exhaust gas. The direction of the ionic flow is dependent upon whether the air/fuel mixture is fuel-rich or fuel-lean.
  • the electrochemical pumping cell pumps oxygen ions into the diffusion layer 12 from the upper porous platinum electrode 30 through the solid electrolyte layer 26 and the lower porous platinum electrode 18 so as to compensate for the predisposition of the diffusion layer 12 to have an oxygen partial pressure equal to that of the exhaust gas, which in a fuel-rich condition is less than the oxygen partial pressure at the stoichiometric point of air and fuel.
  • a fuel-lean air/fuel mixture i.e., oxygen-rich results in the electrochemical pumping cell pumping oxygen out of the diffusion layer 12 in the opposite direction to that just described.
  • the use of a single solid electrolyte layer 26 has the advantage of being simpler to fabricate when compared to multiple electrolyte layers. Moreover, multiple electrolyte layers contribute to functional problems because the oxygen partial pressure in the diffusion layer 12 would be measured in a different location than where oxygen is pumped in and out of the diffusion layer 12.
  • the wide-range oxygen sensor 10 of the present invention takes advantage of the properties of the single solid electrolyte layer 26 to simplify the structure of the sensor.
  • the electrochemical storage cell seeks to maintain an oxygen partial pressure in the oxygen storage layer 14 within at least one order of magnitude from one atmosphere to provide a stable oxygen partial pressure reference value.
  • the constant current source 32storage layer 14 and the diffusion layer 12 are deposited to a depth of about 25 micrometres to about 200 micrometres on the substrate 11.
  • the oxygen storage layer 14 and the diffusion layer 12 are preferably deposited using known screen-printing methods, and are then fired in a furnace at temperatures of approximately 1300 to 1500°C.
  • the distance between the oxygen storage layer 14 and the diffusion layer 12 is about 3 to about 5 millimetres to limit ionic cross-talk therebetween.
  • the oxygen storage layer 14 and the diffusion layer 12 can be formed on the substrate 11 by compressing a porous ceramic/polymer tape (corresponding to the oxygen storage layer 14 and the diffusion layer 12) to a dense ceramic/polymer tape (corresponding to the substrate 11) at locations in the surface of the substrate 11 at which the oxygen storage and diffusion layers 14 and 12 are to be formed.
  • a porous ceramic/polymer tape corresponding to the oxygen storage layer 14 and the diffusion layer 12
  • dense ceramic/polymer tape corresponding to the substrate 11
  • Such ceramic/polymer tapes are well known in the art and are formed using known ceramic tape casting methods.
  • the structure is then fired to dissipate the binder, leaving a porous ceramic layer bonded to the dense YSZ substrate 11.
  • the insulating alumina layer 16 is then deposited through a suitably sized mask to a depth of about 20 micrometres using known plasma-spray deposition techniques, though other known methods, such as screen-printing, could be foreseeably used to achieve similar results.
  • the thickness of this insulating layer can vary from sub-micrometre size to about 50 micrometres, since its function is to prevent deleterious ionic or electrical communication with the substrate 11.
  • the masking technique permits the insulating layer 16 to be selectively deposited on the substrate 11 as shown in Figure 2 to the exclusion of the oxygen storage layer 14 and the diffusion layer 12.
  • the lower porous platinum electrodes 18 and 20 are then deposited onto the insulating layer through a mask to a depth of about 1 micrometres to about 1.5 micrometres.
  • the lower porous platinum electrodes 18 and 20 are preferably deposited using known sputtering techniques. As shown in Figures 5 and 6, each of the lower porous platinum electrodes 18 and 20 is in contact with its corresponding diffusion layer 12 and oxygen storage layer 14.
  • the insulating band layers 22 and 24 are then formed across the width of the wide-range oxygen sensor 10, as shown in Figures 7 and 8, again using known plasma-spray techniques or other known methods with a mask to selectively deposit the insulating band layers 22 and 24 as shown to a depth of about 20 micrometres.
  • these insulating bands which are also preferably formed from alumina, may range in thickness from sub-micrometre size to about 50 micrometres since their function is to prevent ionic or electrical leakage at the periphery of the solid electrolyte layer 26.
  • the insulating band layers 22 and 24 serve to eliminate the formation of a triple point formed where the electrodes 18 and 20 contact the exhaust gas, which would otherwise create a leakage path for oxygen ions into or out of the solid electrolyte layer 26. The resulting ionic current would add to or subtract from the pumping current, thereby creating an output error.
  • the insulating band layer 22 corresponding to the electrochemical pumping cell is located on the wide-range oxygen sensor 10 so that the diffusion layer 12 is partially exposed to permit diffusion of oxygen directly into the diffusion layer 12, as can best be seen in Figure 8.
  • the solid electrolyte layer 26 is then formed by plasma-spray deposition to cover essentially all of the upper surface of the wide range oxygen sensor 10 between the insulating band layers 22 and 24.
  • the lower porous platinum electrodes 18 and 20 are partially left exposed to serve as contacts.
  • the solid electrolyte layer 26 leaves the diffusion layer 12 partially exposed to permit diffusion of oxygen directly into the diffusion layer 12, as can best be seen in Figure 10.
  • the thickness of the solid electrolyte layer 26 preferably ranges between about 100 micrometres and about 500 micrometres. This thickness is sufficiently small relative to the distance between the oxygen storage layer 14 and the diffusion layer 12 to minimise ionic cross-talk between the oxygen storage layer 14 and the diffusion layer 12.
  • the upper porous platinum electrodes 28 and 30 are sputtered onto the solid electrolyte layer 26 so that each one of them is in ionic communication with its corresponding lower porous platinum electrode 20 and 18, respectively, as shown in Figures 11 and 12.
  • the electrochemical storage cell seeks to maintain an oxygen partial pressure in the oxygen storage layer 14 within at least one order of magnitude from one atmosphere to provide a stable oxygen partial pressure reference value.
  • the constant current source 32 of the electrochemical storage cell creates a current flow from the lower porous platinum electrode 20 through the solid electrolyte layer 26 to the upper porous platinum electrode 28. This causes the oxygen molecules in the exhaust gases adjacent to the upper porous platinum electrode 28 to ionise. Because oxygen ions are negatively charged, the ions diffuse through the solid electrolyte layer 26 and into the oxygen storage layer 14 where they give up their excess electrons and recombine to form oxygen molecules within the oxygen storage layer 14.
  • the electrochemical pumping cell seeks to maintain the diffusion layer 12 with an oxygen partial pressure approximately equal to the oxygen partial pressure at the stoichiometric point for the particular air/fuel mixture. If the engine is operating at the stoichiometric point, the oxygen which naturally diffuses into the diffusion layer 12 at its exposed surface will establish an oxygen partial pressure within the diffusion layer 12 substantially equal to the oxygen partial pressure at the stoichiometric point. The difference in oxygen partial pressures in the oxygen storage layer 14 and the diffusion layer 12 will establish a voltage in the electrochemical reference cell (i.e., between the lower porous platinum electrodes 20 and 18, respectively) of about 450 millivolts.
  • the diffusion layer 12 will be predisposed to have an oxygen partial pressure less than or greater than that at the stoichiometric point, respectively. If the engine is operating in the fuel-rich condition, the potential between the lower porous platinum electrodes 18 and 20 will be higher than 450 millivolts due to oxidizable gases, such as carbon monoxide, hydrogen and hydrocarbons, diffusing through the diffusion layer 12 and creating a very low equilibrated oxygen partial pressure. As a result, a feedback signal from the electrochemical reference cell will be relayed to the variable voltage source 34 which regulates the voltage across the porous platinum electrodes 30 and 18 of the electrochemical pumping cell.
  • the variable voltage source 34 which regulates the voltage across the porous platinum electrodes 30 and 18 of the electrochemical pumping cell.
  • variable voltage source 34 will create a potential between the lower and upper porous platinum electrodes 18 and 30 of the electrochemical pumping cell that creates a current flow from the lower porous platinum electrode 18 to the upper porous platinum electrode 30.
  • oxygen molecules will be ionised at the upper porous platinum electrode 30 and flow through the solid electrolyte layer 26 to the diffusion layer 12, the effect of which is to increase the oxygen partial pressure in the diffusion layer 12.
  • the current flow necessary to maintain the oxygen partial pressure in the diffusion layer 12 at the stoichiometric point will be proportional to the concentration of oxidizable gases present, or fully equilibrated oxygen partial pressure, in the exhaust gases according to the diffusion current limiting mode.
  • the potential between the lower porous platinum electrodes 18 and 20 will be lower than 450 millivolts.
  • the feedback signal from the electrochemical reference cell to the variable voltage source 34 will cause a reversal of the polarity as compared to the fuel-rich operation in order to decrease the oxygen partial pressure in the diffusion layer 12 and re-establish the 450 millivolts potential.
  • the potential created by variable voltage source 34 between the lower and upper porous platinum electrodes 18 and 30 will create a current flow from the upper porous platinum electrode 30 to the lower porous platinum electrode 18.
  • oxygen molecules will be ionised in the diffusion layer 12 at the lower porous platinum electrode 18 and flow through the solid electrolyte layer 26 to the upper porous platinum electrode 30, the effect of which is to decrease the oxygen partial pressure in the diffusion layer 12.
  • the current flow necessary to maintain the oxygen partial pressure in the diffusion layer 12 at the stoichiometric point will be proportional to the oxygen partial pressure in the exhaust gases according to the diffusion current limiting mode.
  • FIG. 21 and 22 An alternative embodiment of a wide-range oxygen sensor 110 which also operates partially in the diffusion current limiting mode and which can also be characterised as being readily manufacturable in accordance with this invention is shown in Figures 21 and 22.
  • This alternative embodiment also includes a dense ceramic substrate 111, an electrochemical storage cell and an electrochemical pumping cell disposed on the substrate 111 in spaced-apart relation to each other, and an electrochemical reference cell formed between the electrochemical storage and pumping cells.
  • the electrochemical storage and pumping cells share a single YSZ electrolyte layer so as to facilitate processing and thereby reduce manufacturing costs.
  • this embodiment does not employ distinct porous layers for forming an oxygen storage layer or a diffusion layer, but instead uses a porous YSZ electrolyte layer 122, enabling the wide range oxygen sensor 110 to rely upon the pores and cracks in the porous electrolyte layer 122 for purposes of both oxygen storage and diffusion.
  • the electrochemical storage cell has upper and lower porous platinum electrodes 124 and 116, respectively, disposed on opposite sides of the porous electrolyte layer 122.
  • An oxygen storage region exists in the porous electrolyte layer 122 adjacent to the lower porous platinum electrode 116.
  • the electrochemical pumping cell also has upper and lower porous platinum electrodes 126 and 114, respectively, positioned on opposite sides of the porous electrolyte layer 122. Similar to the oxygen storage region of the electrochemical storage cell, the electrochemical pumping cell has a diffusion region in the porous electrolyte layer 122 adjacent to the lower porous platinum electrode 114.
  • an electrochemical reference cell is formed between the lower porous platinum electrodes 116 and 114 of the electrochemical storage and pumping cells, and serves to monitor the oxygen partial pressure in the diffusion region relative to the predetermined oxygen partial pressure in the oxygen storage region.
  • the porous electrolyte layer 122 and the electrochemical storage and pumping cells are deposited upon a ceramic layer 112.
  • a pair of insulating band layers of ceramic 118 and 120 extend across the width of the wide range oxygen sensor 110 to prevent the leakage of oxygen ions along the interface between the porous electrolyte layer 122 and the lower porous platinum electrodes 116 and 114.
  • the operation of the wide-range oxygen sensor 110 is essentially identical to the wide-range oxygen sensor 10 of the preferred embodiment of Figures 1 to 12. However, as seen in Figures 13 to 22, the processing of the wide-range oxygen sensor 110 differs from that of the preferred embodiment as follows.
  • the ceramic (preferably alumina) insulating layer 112 is first deposited over the entire surface of the substrate 111 to a depth of about 20 micrometres using known plasma-spray deposition techniques though, as before, other known methods such as screen-printing could be foreseeably used to achieve similar results.
  • the thickness can again vary between sub-micrometre size and about 50 micrometres, since its function is to prevent deleterious ionic or electrical communication with the substrate 111.
  • the lower porous platinum electrodes 116 and 114 are then deposited onto the insulating layer through a mask to a depth of about 1 micrometre to about 1.5 micrometres.
  • the porous platinum electrodes 116 and 114 are preferably deposited using known sputtering techniques.
  • the insulating band layers 120 and 118 are then formed across the width of the wide-range oxygen sensor 110, as shown in Figures 17 and 18, again using known plasma-spray techniques with a mask to selectively deposit the insulating band layers 120 and 118 to a depth of about 20 micrometres.
  • the porous electrolyte layer 122 is then formed by plasma-spray deposition to cover essentially all of the upper surface of the wide range oxygen sensor 110 between the insulating band layers 120 and 118.
  • the thickness of the porous electrolyte layer 122 is preferably about 100 micrometres to about 500 micrometres.
  • the upper porous platinum electrodes 124 and 126 are sputtered onto the porous electrolyte layer 122 so that each one is in ionic communication with its corresponding lower porous platinum electrode 116 and 114, respectively, as shown in Figures 21 and 22.
  • FIG. 23 A third embodiment of a wide-range oxygen sensor 210 which operates in the diffusion current limiting mode in accordance with this invention is shown in Figure 23.
  • This embodiment also includes a dense ceramic, and preferably YSZ, substrate 211, an electrochemical storage cell and an electrochemical pumping cell disposed on the substrate 211 in spaced-apart relation to each other, and an electrochemical reference cell formed between the electrochemical storage and pumping cells.
  • the electrochemical storage cell operates between porous platinum electrodes 224 and 232 and the electrochemical pumping cell operates between porous platinum electrodes 216 and 230.
  • the electrochemical storage and pumping cells share a single plasma-sprayed YSZ electrolyte layer 228 so as to facilitate processing and thereby also reduce manufacturing costs.
  • this embodiment employs a fifth porous platinum electrode 218 for the purpose of avoiding the effect of polarisation of the lower electrode 224 of the electrochemical storage cell.
  • the difference between the 4-electrode structure of the first and second embodiments and the 5-electrode structure of this embodiment is that the electrochemical reference cell is isolated from the electrochemical oxygen storage cell.
  • the electrochemical pumping cell operates between lower and upper porous platinum electrodes 18 and 30, and the electrochemical reference cell operates between lower porous platinum electrodes 18 and 20 - thus, the electrochemical pumping cell and reference cell share electrode 18.
  • the fifth electrode 218 is added to form the reference cell between electrodes 218 and 216.
  • the electrode 218 is exposed to the oxygen in an oxygen storage layer 222, but there is not an electronic connection to electrode 224 of the electrochemical storage cell.
  • the advantage of this embodiment is potentially improved performance, though the structure is somewhat more complex.
  • both of the lower electrodes 218 and 216 contact the YSZ substrate 211, permitting the YSZ substrate to serve as the electrolyte for the electrochemical reference cell formed between the lower electrodes 218 and 216. Simultaneously, the lower electrode 218 is exposed directly to the stored oxygen within the oxygen storage layer 222. Similar to the first and second embodiments, alumina insulating layers 212, 214, 220 and 226 are provided and function and described previously.
  • a 5-electrode structure can be formed by depositing a plasma-sprayed YSZ electrolyte layer in place of using the YSZ substrate as a second electrolyte layer.
  • a first YSZ electrolyte layer would be deposited between the electrodes 218 and 224 to serve as the oxygen storage layer 222 and the electrolyte for the electrochemical storage cell.
  • a second YSZ electrolyte layer would then be deposited between the electrodes 218 and 216 and over the electrodes 224 and 216 to serve as the electrolyte for the electrochemical storage and pumping cells between the electrodes 224 and 232, and 216 and 230, respectively.
  • a significant advantage of the present invention is that the construction of the wide-range oxygen sensors 10, 110 and 210 and the processing methods serve to reduce manufacturing costs whilst also making the wide-range oxygen sensors 10, 110 and 210 more readily producible under mass-production conditions.
  • each of the embodiments is fabricated with a planar horizontal structure which does not require the reference gas chambers noted with the prior-art sensors. Accordingly, manufacturing and fabrication constraints associated with the need for complicated geometries are overcome.
  • the planar configuration of the wide-range oxygen sensors 10, 110 and 210 of the present invention permit the use of thermal deposition methods which advantageously facilitate mass-production.
  • Processing of the wide-range oxygen sensors 10, 110 and 210 is also facilitated by using a single electrolyte layer which is advantageous in that it simplifies fabrication as compared to the need to deposit multiple electrolyte layers.
  • the use of a single electrolyte layer overcomes various disadvantages associated with multiple electrolyte layers.
  • multiple electrolyte layers generally create operational problems because the oxygen partial pressure in the diffusion layer is measured in a different location than where oxygen is pumped in and out of the diffusion layer.
  • the wide-range oxygen sensors 10, 110 and 210 of the present invention are able to avoid the potential disadvantage of ionic cross-talk by exploiting the properties of the electrolyte layer.
  • the ionic resistance between the electrodes of each individual cell i.e., between the upper electrodes and their respective lower electrodes
  • the ionic leakage current between the horizontally-spaced pairs of electrodes is small compared to the pumping currents within the electrochemical storage and pumping cells. Therefore, any sensor error caused by ionic cross-talk between the electrochemical storage and pumping cells is negligible.
  • the wide-range oxygen sensors 10, 110 and 210 each operate partially in the diffusion limited current mode, resulting in an output which is proportional to the oxygen partial pressure in the exhaust gases.
  • the wide-range oxygen sensors 10, 110 and 210 are capable of accurately determining the oxygen partial pressure in the exhaust gas of engines operating under both fuel-rich and fuel-lean conditions, as is desirable.
  • Such an operating mode is superior to potentiometric oxygen sensors with respect to fuel utilisation and emissions control by having sufficient sensitivity to accurately determine the oxygen partial pressure in both the fuel-rich and fuel-lean conditions.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measuring Oxygen Concentration In Cells (AREA)
EP93201944A 1992-07-20 1993-07-02 Détecteur d'oxygène dans un domaine étendu Expired - Lifetime EP0580206B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US916555 1992-07-20
US07/916,555 US5360528A (en) 1992-07-20 1992-07-20 Wide range oxygen sensor

Publications (2)

Publication Number Publication Date
EP0580206A1 true EP0580206A1 (fr) 1994-01-26
EP0580206B1 EP0580206B1 (fr) 1997-11-12

Family

ID=25437460

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93201944A Expired - Lifetime EP0580206B1 (fr) 1992-07-20 1993-07-02 Détecteur d'oxygène dans un domaine étendu

Country Status (4)

Country Link
US (1) US5360528A (fr)
EP (1) EP0580206B1 (fr)
JP (1) JP2506551B2 (fr)
DE (1) DE69315131T2 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996011394A1 (fr) * 1994-10-11 1996-04-18 Robert Bosch Gmbh Capteur de mesure permettant de determiner la teneur en oxygene de melanges gazeux
WO2001025778A1 (fr) * 1999-10-01 2001-04-12 Volkswagen Aktiengesellschaft Procede permettant de determiner la valeur lambda des gaz d'echappement d'un moteur a combustion interne
WO2002006811A1 (fr) * 2000-07-19 2002-01-24 Robert Bosch Gmbh Element de detection electrochimique
EP1348950A3 (fr) * 2002-03-29 2004-05-26 Hitachi Unisia Automotive Ltd. Dispositif pour détecter le rapport air/carburant
CN117192179A (zh) * 2023-10-05 2023-12-08 江阴信邦电子有限公司 一种宽域氧传感器的模拟系统及宽域氧信号的模拟方法

Families Citing this family (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5827415A (en) * 1994-09-26 1998-10-27 The Board Of Trustees Of Leland Stanford Jun. Univ. Oxygen sensor
DE19539357B4 (de) * 1994-10-24 2011-09-15 Denso Corporation Luft-Brennstoffverhältnis-Erfassungseinrichtung
KR960024356A (ko) * 1994-12-26 1996-07-20 이형도 광역공연비 센서 및 이의 구동방법
US5762737A (en) * 1996-09-25 1998-06-09 General Motors Corporation Porous ceramic and process thereof
US5970968A (en) * 1997-09-25 1999-10-26 Chrysler Corporation Control of a multi (flexible) fueled vehicle utilizing wide range oxygen sensor feedback
DE19906908B4 (de) * 1999-02-19 2004-02-19 Robert Bosch Gmbh Sensor zur Analyse von Gasen
US6572747B1 (en) 1999-03-08 2003-06-03 Delphi Technologies, Inc. Method for making a wide range sensor element
KR100345233B1 (ko) * 1999-11-08 2002-07-25 한국전기연구원 배기가스를 측정하기 위한 세라믹 가스 센서 및 그를 이용한 차량의 연료량 제어 장치
US20020023480A1 (en) 2000-01-31 2002-02-28 Matsushita Electric Industrial Co., Ltd. Gas sensors and the manufacturing method thereof
US6544405B2 (en) 2000-12-15 2003-04-08 Delphi Technologies, Inc. Sensor coating inhibiting glass formation
US6585872B2 (en) 2000-12-19 2003-07-01 Delphi Technologies, Inc. Exhaust gas sensor
US6638405B2 (en) 2001-09-10 2003-10-28 Delphi Technologies, Inc. Gas sensor and method of manufacturing the same
US20060290525A1 (en) * 2002-09-12 2006-12-28 Andersen Donald P Gas alert for medical gas system
US20050016848A1 (en) * 2003-05-30 2005-01-27 Muhammad Sahimi Oxygen sensor with a solid-state reference and manufacturing thereof
US20080035492A1 (en) * 2004-12-17 2008-02-14 Hilliard Donald B Oxygen Transport Structure
US8057652B2 (en) * 2005-03-28 2011-11-15 Uchicago Argonne, Llc High-temperature potentiometric oxygen sensor with internal reference
US8012323B2 (en) * 2008-03-12 2011-09-06 Uchicago Argonne, Llc Compact electrochemical bifunctional NOx/O2 sensors with internal reference for high temperature applications
WO2010003826A1 (fr) * 2008-07-10 2010-01-14 Robert Bosch Gmbh Élément capteur et procédé de détermination de composants gazeux dans des mélanges gazeux et leur utilisation
US20100170794A1 (en) * 2009-01-06 2010-07-08 Gm Global Technology Operations, Inc. Direct connect oxygen sensor
WO2015025924A1 (fr) * 2013-08-21 2015-02-26 株式会社デンソー Capteur de gaz
JP6488146B2 (ja) * 2014-03-28 2019-03-20 日本碍子株式会社 被膜の製造方法及びガスセンサの製造方法
CN108349223A (zh) 2015-08-18 2018-07-31 威斯康星校友研究基金会 ClO2气体从医疗器械包装膜的释放
WO2017205146A1 (fr) * 2016-05-27 2017-11-30 Carrier Corporation Dispositif de détection de gaz et son procédé de fabrication
CN114923973B (zh) * 2022-05-18 2023-10-20 明石创新(烟台)微纳传感技术研究院有限公司 高原制氧机专用小尺寸氧分压型氧传感器及其制备方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4264425A (en) * 1979-05-25 1981-04-28 Nissan Motor Company, Limited Device for detection of air/fuel ratio from oxygen partial pressure in exhaust gas
US4272329A (en) * 1980-03-03 1981-06-09 Ford Motor Company Steady state mode oxygen sensor and method
EP0052542A1 (fr) * 1980-11-17 1982-05-26 Thomson-Csf Capteur électrochimique des concentrations d'espèces dans un mélange fluide, et système de régulation de la richesse d'un mélange air-carburant mettant en oeuvre un tel capteur
EP0138170A2 (fr) * 1983-10-14 1985-04-24 Mitsubishi Denki Kabushiki Kaisha Détecteur du rapport air-carburant pour moteurs
EP0172746A2 (fr) * 1984-08-21 1986-02-26 Ngk Insulators, Ltd. Dispositif électrochimique
DE3543759A1 (de) * 1984-12-11 1986-07-10 Mitsubishi Electric Corp Luft/kraftstoff-verhaeltnisdetektor

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55154450A (en) * 1979-05-19 1980-12-02 Nissan Motor Co Ltd Air-fuel-ratio detector
JPS6029065B2 (ja) * 1979-07-28 1985-07-08 日産自動車株式会社 空燃比制御信号発生装置
US4487680A (en) * 1983-04-18 1984-12-11 Ford Motor Company Planar ZrO2 oxygen pumping sensor
JPS6027851A (ja) * 1983-07-25 1985-02-12 Toyota Motor Corp 空燃比検出器
JPS6036948A (ja) * 1983-08-09 1985-02-26 Ngk Insulators Ltd 電気化学的装置
US4668374A (en) * 1986-07-07 1987-05-26 General Motors Corporation Gas sensor and method of fabricating same
US4724061A (en) * 1986-08-21 1988-02-09 General Motors Corporation Automotive, internal reference, solid electrolyte, lean oxygen sensor
US4810350A (en) * 1986-09-08 1989-03-07 General Motors Corporation Automotive, internal reference, solid electrolyte, lean oxygen sensor
JPH0635954B2 (ja) * 1987-05-12 1994-05-11 日本特殊陶業株式会社 空燃比検出装置
US5089113A (en) * 1988-07-22 1992-02-18 Ford Motor Company Measurement and control of exhaust gas recirculation with an oxygen pumping device
EP0366863B1 (fr) * 1988-10-31 1994-08-31 Fujikura Ltd. Dispositif de détection d'oxygène
US4980044A (en) * 1989-03-31 1990-12-25 General Motors Corporation Oxygen sensor having a flat plate element and heater
JPH03130657A (ja) * 1989-10-17 1991-06-04 Tokuyama Soda Co Ltd 酸素センサ

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4264425A (en) * 1979-05-25 1981-04-28 Nissan Motor Company, Limited Device for detection of air/fuel ratio from oxygen partial pressure in exhaust gas
US4272329A (en) * 1980-03-03 1981-06-09 Ford Motor Company Steady state mode oxygen sensor and method
EP0052542A1 (fr) * 1980-11-17 1982-05-26 Thomson-Csf Capteur électrochimique des concentrations d'espèces dans un mélange fluide, et système de régulation de la richesse d'un mélange air-carburant mettant en oeuvre un tel capteur
EP0138170A2 (fr) * 1983-10-14 1985-04-24 Mitsubishi Denki Kabushiki Kaisha Détecteur du rapport air-carburant pour moteurs
EP0172746A2 (fr) * 1984-08-21 1986-02-26 Ngk Insulators, Ltd. Dispositif électrochimique
DE3543759A1 (de) * 1984-12-11 1986-07-10 Mitsubishi Electric Corp Luft/kraftstoff-verhaeltnisdetektor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996011394A1 (fr) * 1994-10-11 1996-04-18 Robert Bosch Gmbh Capteur de mesure permettant de determiner la teneur en oxygene de melanges gazeux
US5702580A (en) * 1994-10-11 1997-12-30 Robert Bosch Gmbh Measuring sensor for determining the oxygen content of gas mixtures
WO2001025778A1 (fr) * 1999-10-01 2001-04-12 Volkswagen Aktiengesellschaft Procede permettant de determiner la valeur lambda des gaz d'echappement d'un moteur a combustion interne
WO2002006811A1 (fr) * 2000-07-19 2002-01-24 Robert Bosch Gmbh Element de detection electrochimique
US6694801B2 (en) 2000-07-19 2004-02-24 Robert Bosch Gmbh Electrochemical sensor element
EP1348950A3 (fr) * 2002-03-29 2004-05-26 Hitachi Unisia Automotive Ltd. Dispositif pour détecter le rapport air/carburant
US7122103B2 (en) 2002-03-29 2006-10-17 Hitachi Ltd. Air/fuel ratio detection apparatus
CN117192179A (zh) * 2023-10-05 2023-12-08 江阴信邦电子有限公司 一种宽域氧传感器的模拟系统及宽域氧信号的模拟方法

Also Published As

Publication number Publication date
JP2506551B2 (ja) 1996-06-12
DE69315131D1 (de) 1997-12-18
EP0580206B1 (fr) 1997-11-12
JPH06213864A (ja) 1994-08-05
DE69315131T2 (de) 1998-03-05
US5360528A (en) 1994-11-01

Similar Documents

Publication Publication Date Title
EP0580206B1 (fr) Détecteur d'oxygène dans un domaine étendu
US4487680A (en) Planar ZrO2 oxygen pumping sensor
EP0152942B1 (fr) Dispositif de détection du rapport air-carburant d'un mélange sur une plage allant de largement au dessus à largement au dessous du rapport stoechiomètrique
US4298573A (en) Device for detection of oxygen concentration in combustion gas
US4755274A (en) Electrochemical sensing element and device incorporating the same
US4765880A (en) Air/fuel ratio sensor
EP0142993B1 (fr) Dispositif électrochimique
CA1223041A (fr) Temoin de dosage air-carburant
US5474665A (en) Measuring sensor for determining the oxygen content of gas mixtures
EP0188900A2 (fr) Dispositif électrochimique
JP2968805B2 (ja) ガス混合物中含酸素ガスの相対量の測定方法及び測定デバイス
US4578171A (en) Air/fuel ratio detector
US4724061A (en) Automotive, internal reference, solid electrolyte, lean oxygen sensor
US6562215B1 (en) Planar exhaust sensor element with enhanced geometry
US4615787A (en) Air/fuel ratio detector
JPH0414305B2 (fr)
US4591421A (en) Air/fuel ratio detector
US20100126883A1 (en) Sensor element having suppressed rich gas reaction
US6746584B1 (en) Oxygen sensing device
US5972200A (en) Method for driving a wide range air to fuel ratio sensor
US4747930A (en) Air/fuel ratio sensor
US4666566A (en) Method of detecting oxygen partial pressure
USH427H (en) Air/fuel ratio detector
EP0320502B1 (fr) Procédé de détection de la pression partielle d'oxygène
US10859526B2 (en) Gas sensor with a pump cell

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB

17P Request for examination filed

Effective date: 19940131

17Q First examination report despatched

Effective date: 19960809

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB

REF Corresponds to:

Ref document number: 69315131

Country of ref document: DE

Date of ref document: 19971218

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20000710

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20000719

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20000825

Year of fee payment: 8

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010702

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20010702

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20020329

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20020501

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST